A trading object or trader provides the ability to discover instances of services offered within a distributed system. This paper proposes a Service Discovery Service (SDS) for a CORBA environment that can assist client providers in the construction of their client programs. By sing the SDS, the client providers will obtain knowledge of services with required functionality before writing the client programs to trade for those services with the trader. The SDS gathers XML service descriptions from multiple CORBA traders and can discover information on service types, service interface definitions, and service offers. It can be thought of as a search engine for service descriptions and query is possible via keywords and XML query languages. It is also accessible by both CORBA and WWW clients with a possibility to enlarge search space by federation of multiple SDSes.